Dialight reports zero failures in high-power LED traffic signals

Oct. 11, 2005
Dialight has used 17 million Luxeon LED light sources from Lumileds in its traffic signal products, without a single field failure.
In the past 7 years, Dialight Corporation has used in excess of 17 million Luxeon light sources from Lumileds in its traffic signals and other products. The company says that it has not experienced a single LED-related field failure in seven years of building Luxeon-based traffic signals.

"We use Luxeon LEDs because they can withstand environmental extremes, dissipate heat more effectively, and handle more current without degradation," said Gary Durgin, Dialight Vice President of Strategic Business Planning.

"These are vital features when you're talking about a mission-critical application like a traffic signal. Having a sudden failure…is simply not acceptable. It not only requires that traffic departments drop everything and replace the light, it can cause an accident."

Lumileds says that the Luxeon lensing system, heat dissipation capabilities, zero-stress technology and other factors associated with the engineering of its package combine to maximize the effective life of the LED and prevent premature breakdowns. The ruggedness of the Luxeon package stems from features including:

* Silicone lensing: While the lensing systems of conventional LEDs use an epoxy that discolors and reduces the usable life of the LED, Luxeon LEDs employ a special silicone-based encapsulation that eliminates discoloration.

* Thermal management: Luxeon LEDs offer high maximum junction temperature, low thermal resistance, and a package design that maximizes heat dissipation, enabling efficient and effective operation in high heat environments.

* Zero-stress: Luxeon's encapsulation system provides a zero-stress environment on the die and wire bonds, increasing the package robustness and reliability. Other LEDs employ a rigid epoxy material to surround the die and wire bonds that can put stresses on the die attach, wire bonds and semiconductor material. Luxeon's stress-free environment enables higher junction temperature operation and delivers reliability in harsh environments such as power temperature cycling.

"Dialight's traffic signals bake in the sun and freeze in the snow, day after day and year after year," noted Jason Posselt, Director of Product Marketing for Lumileds Lighting. "The fact that Luxeon emitters can maintain their performance under these conditions proves that they can survive anywhere, and that is directly connected to the way they are engineered. Not all high-power LEDs are created equal, as Dialight has discovered firsthand."